A related-art semiconductor device including a bonding pad is now described. FIGS. 13A-13B are sectional views for illustrating the related-art semiconductor device.
When a cross-section in the vicinity of a bonding pad is seen, a first metal film 132 is formed on an interlayer insulating film 131, and another interlayer insulating film 133 is formed so as to cover the first metal film 132. Metal plugs 134 are formed and arranged on the first metal film 132 by known photolithography and etching or by a CMP technology. A second metal film 135 is formed above the first metal film 132 so as to be connected to the first metal film 132 via the metal plugs 134. A protective film 136 has an opening above the second metal film 135. Further, the protective film 136 covers the second metal film 135 other than at the opening in the protective film 136.
In this case, embedded tungsten plugs are used as the metal plugs 134. All the metal plugs have the same diameter size close to a smallest diameter that can be formed in accordance with a process rule, and a surface of the second metal film 135 is flat (see, for example, Patent Literature 1).